Scientists have been studying the payload returned to Earth by NASA’s Stardust spacecraft for years in search of the perfect primordial sample, and now they may have finally found it. The team has discovered evidence of seven interstellar dust particles weighing just a few trillionths of a gram, but this is the first time we’ve found any amount of material unaltered by the birth of our solar system.

Stardust was launched in 1999 with the mission to coast through the dusty tail of comet Wild 2. The craft successfully completed this phase of the mission in 2004 and returned the sample container to Earth in a 2006 flyby. One of the reasons researchers were so anxious to examine cometary dust was that it was believed the material streaming from Wild 2 would be a repository of interstellar dust unsullied by the heat of the sun — pristine pre-solar material. That turned out not to be the case. The matter in Wild 2 was heated and transformed by the sun at some point, then carried toward the outer solar system to form a comet.

Luckily, the spacecraft had a second mission while it was waiting to intercept Wild 2. Between 2000 and 2002 Stardust pointed its dust collecting panels toward deep space and waited for particles to stream in toward the inner solar system. The panels were covered with a thin layer of aerogel, a silica-based material that is 99.8% empty space. The system was designed to slow and capture interstellar particles without incinerating them — no small feat as these miniscule specks are often traveling at 15,000 kilometers per hour.

It has taken years for the team to carefully examine the aerogel for evidence of interstellar dust, but they have finally announced success. With the help of over 30,000 volunteers looking at microscopic images of the panels, the team has identified seven probable dust impacts. From these locations, the team found two good samples (nicknamed Orion), each one with a mass of 3 trillionths of a gram. A few more impacts left a residue that can be analyzed, but the intact particles are the crown jewel.

The next step is getting the samples out of the aerogel and into instruments where they can be analyzed and their composition confirmed. These little chunks of aluminum, iron, and magnesium could be what seeds solar systems. This is us just a few billion years ago.